3.A.1.121.6MsrD of 487 aas and 0 TMSs. Involved in macrolide resistance (Zhang et al. 2016). Two ATPase domains are present in tandem. The membrane constituent is not known. However, Iannelli et al. 2018 suggested that MefA (TC# 2.a.1.21.1) can function with MsrD, and therefore that this MFS exporter can function as an ABC drug exporter. However,
the data presented seem inconsistent with this suggestion. The two genes
encoding these two proteins are adjacent to each other, suggesting that
they may somehow function together (Iannelli et al. 2018).